90 Camry Strange Start/Stall Problem

[sroger007]

3S-FE Auto very strange starting/stalling problem - Initially the car when cold would run great for about 20min but would start to lose power and die. It was then very difficult to start if at all. Cold she started fine. Now she only starts with timing fully retarded and run (although it has no power) for about 2 minutes then coughs/cuts out and dies. Restarts with a few cranks but stalls about a minute or less later. Usually won't start on the third try and doesn't start for 30 minutes plus after that. Static timing is bang on - crank pulley at TDC and camshaft markings align – belt is new and properly tensioned. The fuel pump is noisy but it maintains pressure in the fuel rail at 40psi at idle and holds for better than 5 minutes after the engine is turned off. PIN checks on sensors (air flow meter/throttle position/cold start injector and sensor/temp sensor/distributor pick-ups and coils etc) seem to be in spec regarding resistance values. No ECU codes – spare ECU and relay swapped in also netted no improvement. ISC valve was also removed and cleaned – no improvement. No leaks on the intake side. EGR holds a vacuum but I have no idea if the valve itself is functioning OK. I'm pretty sure the EGR is not in play after only 2 minutes at idle. Any ideas as to what is causing this problem? What sensors are likely to be sending a signal to the ECU or change state after about a 1m30 of idle – I'm thinking this might be the cause of the stall. If not sensors maybe it's somehow distributor related. I've been farting around on this problem for a week now and getting peeved. Any ideas?

[Kep]

My first inclination is the coil. You said that you did pin checks. Did you check the coil? You might want to go ahead and remove it and look at it visually for cracks.

Since it happens after the car warms up (I would say that it is plenty warm after 20 mins to be concerned about the fuel pump) but it starts again after cooling it is likely an electrical or sensor problem. Things that affect the ECU that I know of are the igniter, the MAF sensor and the temperature sending plug (green, at the return hose) and the pickup coils on the distributor body. There is also an EFI relay (I believe Electronic Fuel Injection) that could be struggling. Curiously, but it doesn't seem "right" the ignition switch also has an effect on the circuit.

Cleaning the ECU wouldn't be a bad idea but, like you, I don't think that is your main culprit.

Mine was doing the opposite of yours (would only start after warming). However, the thread may jog a thought or two: http://www.toyotanation.com/forum/t106779.html

Good luck, they're worth the trouble.

Kep

[sroger007]

Originally Posted by Kep

My first inclination is the coil. You said that you did pin checks. Did you check the coil? You might want to go ahead and remove it and look at it visually for cracks.

When you say cracks are you referring to cracks in the coil or the cap. The capand rotor looks OK and a resistance check of the coils (primary and secondary checks out) as does pick-up resistance and gaps.

Since it happens after the car warms up (I would say that it is plenty warm after 20 mins to be concerned about the fuel pump) but it starts again after cooling it is likely an electrical or sensor problem. Things that affect the ECU that I know of are the igniter, the MAF sensor and the temperature sending plug (green, at the return hose) and the pickup coils on the distributor body.

MAF and temp sensor resistance test OK. Where/what is the ignitor?

There is also an EFI relay (I believe Electronic Fuel Injection) that could be struggling. Curiously, but it doesn't seem "right" the ignition switch also has an effect on the circuit.

Cleaning the ECU wouldn't be a bad idea but, like you, I don't think that is your main culprit.

Cleaning the ECU? Not a clue what you mean here, however I did replaced the ECU with a spare ECU with no improvement

Mine was doing the opposite of yours (would only start after warming). However, the thread may jog a thought or two: http://www.toyotanation.com/forum/t106779.html

Nothing "jogged" yet but I'll keep at it

Good luck, they're worth the trouble.

Kep

[sroger007]

OK I've found out where the ignitor is and basically what it does. Can anyone explain to me what happens if the ignitor fails - is the only option no spark. Is there any middle ground on a bad ignitor - ie a poor spark? Is there any way to test an iginitor other than substitution?

[Doctor J]

The problem like yours is hard to diagnose without actually checking the car, so Kep just gave suggestions based on his experience.
I was working on the car with similar symptomps that was not fixed even by cert. toyota tech with 20 years experience. The problem there turned out to be that one plug in 14 pin computer connector was just pushed into the cavity, but not clicked (locked) in. I discovered this isuue by starting the car and slapping the area near computer, which caused the engine stall.
The computer had no trouble codes stored, because the problem was too brief to set a code.

Noisy fuel pump means restricted fuel line. Camry uses dynamic in-tank pump, so if the output flow is limited, the impeller will just agitate the gas rather then transporting it to the injectors. Ideally, the pump must be pressure and flow tested.
The coolant temp. sensor can break internally, when the lead wires from thermistor inside could get separated from the brass male terminals on the sensor itself.
My recommendation is to start the engine and shake wires near sensor connections, while observing effects on the engine operation.
If it will not reveal anything , please search my threads for specific instructions about individual components.


If igniter fails, the spark will be abcent.

[Doctor J]

The purpose of igniter is to trigger the spark by interrupting current that goes trough the coil(same as points on old car).In addition, it does it with time delay/ advance that corresponds to the timing change based on the engine operation condition (load, temp, rpm).These signals are processed by the engine comp. and sent to igniter via IGT wire. This is called electronic spark timing/control.

[sroger007]

DOCJ - I know this one's going to be a real bear to solve - hense why I put so much detail into the original problem/syptoms. I'm usually pretty good at trouble shooting my cars but this one has got me stumped. I had a similar problem with my 85 Supra some years back - there were no codes so I check about a zillion things and low and behold the ECU was pooched.

Since you mentioned it I checked the ECU connector just to be sure all the receptacles were secure - if you've seen it there's a good chance it can happen again - however all looked good.

Thanks for the fuel noise tip. I'll find the resistriction in the fuel line and fix it - it has a bastardized fuel filter installed so maybe this is where the restriction is. Flow might be a problem at speed or load but at idle pressure was 40psi at stall so there was fuel available.

I get what visually looks like a good spark so I will assume the ignitor is OK.

As you have suggested I'll wiggle/bang at sensors etc some more to see if I can find a fault. I've done this a bit so far but because the engine doesn't run for very long I don't get too far.

I've tested the resistance of the temp sensor at cold, warm and hot. It tested to spec.

[Kep]

sroger007,

Sorry, I meant cleaning the EGR valve, not the ECU --

"Cleaning the ECU EGRouldn't be a bad idea but, like you, I don't think that is your main culprit."

If you are getting good spark at the time that the car isn't starting that tends to eliminate most of my concerns.

The crack I suggested to look for would be in the coil itself. You probably couldn't see it just by taking the distributor cap off. You will probably need to remove the distributor and maybe the coil itself. However, if you have good blue spark this is a real low possibility.

Keep digging, sooner or later you will find it.

Kep